Estimate or governed quotation
Estimate Engine
The Estimate Engine provides an indicative planning range from the information supplied. It is not a binding quotation. Open, complex or unusual work proceeds only after engineering and commercial review and a written proposal or quotation.
Explore an indicative estimate →Instant Engagement
An eligible governed Service Product produces an exact resolved quotation from its approved, version-controlled definition. You see the price and service boundary before accepting it. Prepaid products offer checkout only after acceptance.
View governed services →What the displayed price includes
Each published Service Product has an approved pricing model in EngOS, which may be fixed or resolved from its governed formula, duration, rate and travel controls. Before acceptance, the website identifies the service fee, currency, VAT treatment, inclusions, exclusions, prerequisites, quotation-validity period, cancellation policy and any permitted travel or client-selected duration adjustment.
The issued quotation then shows the subtotal, VAT amount where applicable and total payable. Acceptance records the exact Service Product version, scope, commercial values, terms version and accepting identity. Stemma does not change that accepted price without a separately agreed scope or commercial change.
Only a Service Product shown in the Instant Engagement selector is available for immediate quotation. If no Service Product is published, no instant quotation, Paystack checkout or charge can be initiated; open-scope work remains individually quoted.
Secure checkout for prepaid services
Where an accepted Service Product requires prepayment, EngOS creates a hosted Paystack checkout for the exact accepted total and currency. Paystack, not Stemma, collects your card or bank credentials. EngOS verifies the provider's transaction result server-side before treating the engagement as paid and retains the payment reference for reconciliation.
A payment link does not alter the accepted service scope or price. A pending, cancelled, expired, failed or unverified checkout is not treated as completed payment. Our Refund Policy and Cancellation Policy apply to Paystack-funded governed services.
From acceptance to completion
Every governed Service Product carries its own delivery mode, delivery or session duration, required preparation, minimum booking notice, booking horizon, required client inputs and completion evidence. Those product-specific controls determine the delivery timeline and take priority over a general estimate.
- Eligibility and quotation. EngOS checks the request against the published scope and issues a quotation with a visible validity period.
- Acceptance and commercial clearance. The authorised client accepts the exact quotation. Where prepayment applies, delivery scheduling proceeds after Paystack payment has been verified.
- Scheduling. Available delivery windows are offered within the Service Product's governed booking horizon and subject to its minimum-notice and preparation requirements. A delivery date is confirmed only when a slot is booked.
- Delivery and closeout. Stemma performs the included service and records the required completion evidence, deliverable or review note. Any follow-up outside the accepted boundary becomes a separately reviewed scope.
The selected Service Product and confirmed booking are the customer's exact delivery timeline. If a requested date is not yet confirmed, it is not a promised delivery date. Rescheduling and cancellation notice periods are governed by the accepted product policy.
Visible before acceptance
Prices are shown in the currency stated on the quotation, ordinarily South African rand for South African services. The website and quotation state whether VAT is inclusive, exclusive, zero-rated or out of scope and show any VAT amount charged.
Travel is never assumed. If a Service Product permits travel, the website identifies the governed distance and travel-time treatment and includes the resulting amount in the quotation. If travel is not permitted or the route is outside the product boundary, the request is routed for engineering review rather than silently added to the price.
Scope changes and unavailable services
Missing critical information, new design, certification, site risk, procurement, construction, unusual commercial terms or another material departure from a Service Product does not qualify for automatic purchase. It moves to Stemma's controlled review route and may require a new proposal, price and timeline.
Published services may be revised, retired or temporarily unavailable. This does not rewrite an already accepted quotation. For cancellation or refund outcomes, see the Cancellation Policy and Refund Policy.