Loss of cell phone returned for repairs

I purchased a Nokia lumia in 2017 in January but however in December my cellphone stopped working and I had to take it back to the store. The phone was taken away for repairs but up to today I haven't got the phone back. I tried to check on how the process is shaping up but the staff told me to come durin the week b4 12 so they can easly contact vodacom. I never succeeded because iit was so inconvenience for me to visit the store cos of work. I visited the store couple of times with no success. Right now I am unable to claim my fone back because I lost the relevant purchase papers with the ime number. The store can't trace it back because I dnt have the box n proof of purchase. I have worked so hard to purchase this cellphone n loosing it pains my heart. I am not willing to do any business with the store. Good luck. The total purchase of the fone was R2000.