Student Loan Deletion in Collections - Help!

Okay so here's my deal:

I've been religiously paying off my student loan to the collections agency since 4 years ago. My balance has gone from $10,000 to $1800. I'm worried now that my account wont' be deleted off my credit report. I've checked out the pay for deletion letters but I've noticed that they indicate no acknowledgement of the debt but in my case, I have acknowledged the debt because I've been paying it off all this time! What are my options in getting this debt removed when I pay it in full?

Also, I do have another debt with the same collection company for $8000 and I just started paying it off. My 7 years is up next Feburary 2012 - did my 7 years get renewed when I started paying or does it start from the original date? Please advise! Thanks