vodacom tablet

2 August 2014 my husband took a contract with Vodacom for Samsung Galaxy S (tablet) from Tiekams EL It gave problems from DAY1 - switching off at will. my husband purchased it for a GPS in JHB + more than once found himself stranded. We returned the tablet to Vodacom (via Tiekams) at least 4 times. Twice we didnt even take the machine out of the shop before finding that it was still faulty and handing it back in again. we collected the tablet from Tiekams only to realise that the backlight no longer came on. We returned the tablet to Tiekams on the 24 Jan 2015 and we still dont have it back. Meera at Tiekams told us that it had been returned to them with a crackd screen and she had returned it to Vodacom. On investigating further we found that she does have it, and now wants to argue with the courier service to repair the screen. I have spoken to Samsung. They cant understand why Vodacom keeps returning a faulty machine to us. They should swop it out. Vodacom refuse responsibility and so does Tiekams. Meera at Tiekams says she is dealing with it, but does nothing. We keep paying the instalment nd no-one helps us from VODACOM When oes this become theft?