Consolidated Student loans but thinking off paying off the whole loan. Would the consolidator allow it?

Hi i've consolidated my student loans which is around $23,000.00 and today i got the statement from the consolidater giving me the whole amt i need to pay off in 20yr s with their payment schedule. With their payment schedule, i'll be paying off arnd $43,000.00 with interest, principles with a payment of $180.00 every month for the next 20 yrs. When my dad happened to see the statement he said he'll help me out w/ my student loans and if i go w/ the consolidation payment plan i'm paying the extra $20,000.00 which i dont even owe in student payments to them for no reason and that additional $20,000 i'm paying em is just money down the drain. He wants to me call them and tell them i've changed my mind and not decided to proceed w/ the repayment plans and looking for alternative ways to pay off my loans. The problem is i signed the promissory note and everything so now i'm not sure they'll honor my change of plans. I'm in a big dilemma here and not no what to do. Somebody pls help me out.