Vat Issue

Dear Freind,
 
Myself Dharmendra Kaushik need some clearification regarding DVAT.
 
1. When any company sold it Old computer or motor vehicle, Govt. charge VAT while on same at the time of purchase input credit not allowed. So its calledup double taxation which is against the Law.
 
2. When a person sold his old  car they didnt pay the vat why.
 
Please Revert me ASAP. (With notification No., if applicable.)
Looking for a positive response.