Rotten service from MrP

If I could give a zero star rating I would. I went to Mr P over a month ago to change my number I filled in a form and left it at the store reassured my number would be changed. I have been struggling the whole weekend to pay my account I cannot go to the store to make the payment as I just had a major operation and I am bedridden. I been trying to make the payment on the app and I get an error message. I tried via what's app and I got an error again. I spoke to one of your unhelpful and rude agents PROMISE. This girl knows nothing about customer service I ask her to help me with my query she's adiment I need to go into the store to change the number I tell her I already did it. She says there was nothing received on their side for such a request. On top of that for something this simple this girl takes more than 5 minutes to respond and wastes my time still to tell me she can't help. Now what must happen? Will my account stay in arrears because someone at mrp didn't do their jobs? This is the most disgusting service I have received from a retailer I have supported for years. Your agent dealing with the what's app chats needs to be trained more as they are clueless about what actual customer service is especially that girl promise. I need to pay my account and I NEED ASSISTANCE URGENTLY.