LImitations to guarantee

 No. If your guarantee is for a specific loan, the extent of your liability on the guarantee will diminish with the amounts paid. If the lender wishes to increase the loan against your guarantee, the financial institution will either have to obtain a fresh guarantee from you or seek your written consent to the continuation of your guarantee for the increased amount. In the case of overdraft facilities, generally, the guarantor will remain liable up to the limit he/she has guaranteed for and any increase of the limit will require the guarantor’s consent.

now since they have gone for increment in the loan amount without ur permission, your liability has ceased to exist now.

you are liable for what you have gauranted nothing more or less.some important advice to gaurantor-----in case of car loan while signing as gaurantor please write ---in case  of default and/or disposal of vehicle by bank --prior intimation shal be given to the gaurantor