NOKIA M/P LUMIA 710 Win. 7.5, not working

Location/place: Bangalore

Name of company/service: Infinity Retail Ltd, Trading as Croma GF, 45/1-1,1, Jaya Nagar,Bangalore- 560078,

Dear Sir,
I purchased NOKIA M/P LUMIA 710 Win. 7.5 on 20.04.2012 for Rs 15549/- from Infinity Retail Ltd, Trading as Croma GF, 45/1-1,1, Jaya Nagar,Bangalore- 560078, Phone No 18002583636, Concerned person named Suraj cell No. 09535232641.
from 22nd April on ward I was facind problem of no signal from AIRtel, hence the phone was dead.
I immediately went to airtel Benergatta road, they said all settings are ok, there is problem with hand set.
Went to croma they did some settings and phone was working.
On 21st May when I landed at Delhi, there was no signal,I rushed to NOKIA care , Net dot solutions, Tilak Nagar delhi, No. 01145685624. They could not resolve the issue and asked me to leave the phone for 6 days (which was not possible), as it is to be sent to their head office. In turn they have charged Rs.1440/- as one year extended guarenttee from me.
On my return I contacted CROMA on 28. 05.12 and they sent it to NOKIA Care Jaya Nagar and handed over the phone back to me on 6.06.2012.
Since every now and then the phone is not working, no internet, outlook etc. and I have visited Nokia Care Jaya Nagar number of times, I am totaly disappointed and frustrated hence I don’t want to use this phone any more my amount of Rs.15599+1440=17439 may please be refunded to me either by CROMA or NOKIA. I may please be contacted on 09686204208, E-mail, [email protected]