Contract phone not working

I have upgraded my contract on friday with vodacom call centre, at first i wanted to cancel my contract for the bad attitude and operators being unprofessional with their work, but when i was about to cancel, the lady that helped me with the cancellation, she apologized on behalf of vodacom then i proceeded with the contract by not cancelling. Now i have received the phone on Monday April the 4th. the phone only worked for 2 and half days. The phone is frozen now not working. So now they are telling me that they going to arrange a courier to come and collect the phone, then i will receive it back after +/- 7 days.... What will i be using at that time. I'm a technician who is always on the road. If vodacom don't fix this matter this weekend, i guess they must cancel my contract. This is the second problem i experienced with vodacom in my family within 2 months... like now i keep on borrowing colleagues phones to insert my sim card to check my smses and missed calls. So must i proceed doing that for the next 7 working days. CANCEL if the matter is not resolved quickly.