No Calls or SMS for week

Why is it when you do not pay your cell phone account they have the right to take legal actions and demand the money, but when they ***** up, you can do nothing? I really would like to cancel my Cell C contract without paying a sent for the remainder of the contract. I have purchased an iPhone 5S from someone during Feb 15. I did a sym swop from Micro Sym to Nano Sym. The phone worked perfectly until 28 May 15. When I got home in the afternoon, I saw that my phone shows the carrier (Cell C 3G) without any signal strength. I restart the phone without any success. At first a though it was just bad signal. Suddenly my friends and family asked me on whatsapp why they could not reach me, because they are trying to phone me but keep getting voice mail. Then I notice that No calls can be made and not sms's (in or out). I check the emei number on the internet, and all good, phone is not blacked or blacklisted. I went to Cell C (Mall @ Reds) for a sym swop and paid over R100. Nothing changed, could still not use my phone for calling and sms. THE SPACE IS TO SMALL DO TYPE COMPLETE REPORT. CONTACT ME FOR ALL DETAIL.