Micromax — delay in replacement

i have purchased canvas A117 in march14 but in jan15(within warranty) it has got serious problem of switching on then i have submitted it to service centre indore M.P. they committed to resolve problem within 15 days..but again it has got the same problem and i submitted once again on 28th of feb15 and i came to know that it has severe problem in motherboard and unable to serve anymore but as its in warranty so company will replace the handset by same model or upgraded model. but even after more than two months service centre is making me run behind every 7-8 days and still unable to deliver my replaced handset. making contact directly to customer care of Head Office has also not worked. kindly do the needful.