Contract questions such as these can be tricky. I am guessing that the front of the contract probably refers to the back of the contract in some way, or else you had to sign or initial the back of the contract. Or possibly the pages are numbered as "1" and "2", or there is something to tie them together as one document in some way.
If not, then you may be able to argue that the print on the back was not included and agreed to in your particular case.
As far as what the sales rep said: Generally in a contract case, you look to the "four corners" of the agreement (that is, what is written on paper) and what is SAID is not relevant. The contract may even say that in print. So what is said may not be relevant.
On the other hand, this could also be a DTPA (Deceptive Trade Practices Act) case. You would have to show that the salesman was deliberately misleading, beyond mere "puffing" (normal sales talk) and/or that the contract itself was deceptive and misleading.
A DTPA case is "trickier" than a regular contract case, because there are certain notices that must be given in a timely manner, under the law.
Once you finish analyzing the strengths and weaknesses of your case, you may want to approach the other company and try to settle the matter, or contact an attorney for further help (especially if you decide to go with Deceptive trade), and/or file the case in a small claims court. Be aware that if you are filng deceptive trade there are certain legal steps and notices PRIOR to filing a suit.