Grubbs Infiniti

I purchased a new Infinity QX60 on 8/17. The contract included Grubbs (Texas dealership) paying my Arkansas sales tax. First thing I noticed is that the loan was for a higher amount than the contract amount which they acknowledge but have not resolved. The second thing is they haven't paid the sales tax, which is due shortly and if delinquent, has a 10% penalty attached. I have made numerous attempts to get a resolution and can only get assurances from my salesman. I have spent too much time on this and don't know where to turn?