Edgars breach of credit agreement

I have been an Edgar's customer for 23 years. I am on the 6 month interest free account and since RCS took over we are being charged ridiculous interest. They charge you for an sms they send you a letter and the calls you receive from them. This is insane and I'm sure is against the credit regulations!!. There was NO notification sent that our terms and conditions will be changing. I'm sure if they did we would have settled our account and not do business with them any longer. They need to be taken to account and stop ripping people off