Nokia Lumia 510

Having upgraded my phone to a Nokia Lumia 520 in April.I had never worked properly, it was sent back for repair a month ago.I was refused a replacement at the time being told it would take a week to 10 to repair. I was not happy with the managers attude in the shop. I had to buy a Sim Adaptor to use in a old phone as thay did not have one in the shop.It did not bring up all my data. For three months i have payed for this phone, i have an insurance as well which i thought this sisuation would cover