Return StackSwap's renewal-negotiation playbook for a specific vendor: leverage points (why they will discount), price-anchor alternatives to cite, a calibrated discount ask, a walkaway script, optimal timing window, and contract-trap callouts. Pass `monthlySpend` to compute target savings. Optional `contractEndsIn` flags compressed-timeline adjustments. Authored from operator experience across major B2B SaaS renewals (Salesforce, HubSpot, ZoomInfo, Apollo, Outreach, Salesloft, Smartlead, Gong, Clari, Chorus, Avoma, Fireflies, Clay). Use when the user mentions a renewal, a price increase, or 'we're up for renewal' conversations.