Ever Changing

I Have 2 accounts from Homechoice 1 for a couch that i should be paying R299 and headphones that should be R68.00. i have been paying my account regularly and on Debit order but for some reason for the last 2 months ive been recieving calls on making arrangements to pay my account and im a bit confused because i should have a debit order. Now the topping of the cream is im being told that the amount is now 402.00 monthly on both accounts. when i called the customer care dep i was told that thats the amount but no one can break it down to the correct amount as the innitial agreement i have with them shows a different amount. Another thing i was told was because they moved system but wont acknowledge the fact that their numbers are incorrect. i have been a loyal customer to homechoice but will not be bul**** into paying something i did not sign up for and to me this is breach of contract. If no one fixes my account i will be forced to take legal action.