Bad service, point blank period

In October I sent my phone in for a repair that iPhone said was software. Mtn requested +R6000 to which I declined. Today I went to collect the phone after paying R330 last week. I got to the office, charged the phone n switched it on, to my surprise the phone had a background picture (a stupid smoking cartoon character) and requested a password which was constantly denied time n again. When I sent the phone in it was clean