Mahindra And Mahindra — bad service from pothen autos

Hello
On[protected] we deliver our mahindra power plus, veh. No:kl 43 k4781 to your authorized dealer pothen autos for second service (10000 km). On the same day one service advisor (Mr. Prasad, mob: [protected]) called and told me that, they found one metal piece from the engine of the above mentioned vehicle while dispensing oil from the engine. He told me the vehicle will only return after one week for detail check up. But they didn't called me till one week. So one day i directly went to pothen autos for enquired about my vehicle. But they told their servicing is not completed and will come after two days. The third day they called me and told servicing is completed and take the vehicle. They were not willing to give any guarantee on the engine and vehicle. They open the engine and checked. Then how can we trust that there will not be happen any complaint from that vehicle in future. So you must give one written guarantee from your side or do further actions.
Awaiting your valuable reply.
Regards
Rajesh. R
[protected]