no delivery of my tablet since it went for repairs

since my tablet has been collected for repairs and no show i have called and every time i get the same answer that i will receive my tablet within 10 working days which never happens, i am being told that an sms was sent to me to inform me of when to expect my tablet and every time i have to explain that i have not recieved such sms really upset that they do not waist time in deducting montly installments but every time i am asking about my tablet i do not get a straight answer i am paying for goods that i dont have with me that really upset me