Breaching payment agreement

In November 2015 I bought a fridge from house and home on credit. As a foreigner I was told that I have to pay 50% deposit which I did. Before signing the contract I was told that the first instalment will be in 3 months meaning end of February 2016. In January I received an sms that my account has nt been paid. I contacted them and told them about the agreement of which they said they made a mistake. I have jus received another sms with double the amount to be paid end of January in contravention of wat we agreed. I am disappointed and feel shortchanged by this action. House and home use lies in marketing, duping customers into signing contracts. My instalments must start in Feb but already they are spoiling my name.