PAY JOY PHONES

I'm very dissatisfied with pay Joy 3 phones later all fully paid and I experience such problems. So my phone keeps being blocked. I called and I was advised to go to the shop where I bought the phone fine I went there the consultant removed the App but my phone wouldn't unblock so he advised I call PAY JOY call centre. 2nd time round I call and the consultant advises me that I must call my network provider and find out what the issue could so I call both my network providers and they advise everything is okay on there side which I believe because I've been using my sim cards on a different phone for the past 3 days and I haven't been having issue but immediately when I put in any other network on the PAY JOY phone it doesn't pick up the sim cards still showing as blocked.