No after sales service

Ordered two licences and immediately realised that I had bee over-selled on my requirements by Erik Husonovic-Majic, the smooth salesman from Smartsheet. I requested that I only require one licence for now and they informed that I MUST purchase two licences. No after sales service, refuse to amend the invoice so i haven't paid and all I get from them is silence. I will be using Monday.com for our organisation.