Planet Fitness DISHONEST SALES

I recently signed up for a new contract. In these discussions with the sales person the monthly premium would drastically reduce if i signed up for Sanlam Rewards. This requires a once of payment of R875. I went in last week to make this payment and was advised the payment is now R1500. The Salesmen, Mohau, agreed that we never discussed a time limit. He was also surprised that the amount had changed to R1500. How can Planet Fitness expect me to pay the new rate if their own staff were not aware.