Should vat be paid for reimbursement of spare cost?

Dear Sir,

I am from Kerala. I run an authorised service center for a cellphone brand. Every month my company service warranty handsets, for which I claim the service charge and spare charge+CST cost from the cell phone company. The spares are purchased interstate from the cellphone company, during which I pay 12.5% CST. When I am reimbursed, I am paid the original purchase price of the spare along with the CST I paid for procuring the spare. Also, not all claims are accepted; and some claims are rejected whereby I lose money both in terms of service charge, and the spare cost

My question is:

1. Do I need to pay VAT on the spare cost reimbursed from the company, though we are not making any profit from the transaction?

2. How should I account for the claims lost, and hence lose of spare?

3. Should I pay VAT for the spares that were used, but claim rejected?

Awaiting you reply.

Thanks and Regards,

Anwar Azad