Changing detail at mr price without sucess

For more than 2 years I am trying to change my details wihout any sucess. I have been to 3 different shops. Complete the nessesary form. Nothing changed. I tried the app more than 5 times. Every time they tell me within 24 hours my details will be upadeted. Not true. I still dont receive any statements or be able to use the app. I am so frustrated and fed up. I tried to phone but all respind I get from customer service is a Sorry this number is not in use. Or it put me through to the app. Please help.