Windows 7 product un-readable, can't activate Windows

I'm new to the forum, haven't really posted since I joined in 2012 so not sure where to post this, but this seemed to be the most logical place to post it.

Recently a friends laptop, which was given to me to fix, had 46 viruses which corrupted Windows and the recovery partition on a HP Compaq Presario CQ61 laptop. I proceeded to re-install windows with what I assumed to be the correct recovery discs for the laptop, it turned out they weren't. I was on Microsoft support for an hour and they that the product key which I have (recovered using a product key recovering software) was an OEM-SLP license, which I didn't know at the time of using the product key recovery software, and that HP support was the only option.

After spending a further hour on HP support they also proceeded to tell me that they would not help because the laptop is out of warranty and I would either have to pay for a technician to come out, roughly £150 pounds, or buy new recovery discs, £40, neither option my friend can afford.

Unfortunately she gave me the discs for her old HP laptop and no longer has the recovery discs for her newer laptop. The product key, the COA one on the bottom of the laptop, is rubbed off and you cannot make out what any of it says. Is there any other option to try to activate Windows or do I have to buy a new product key or recovery discs?. Was reading on another forum post that I might be able to do telephone activation, wait for a real person to answer, give them the OEM-SLP license and explain that the one on the bottom of the laptop is rubbed and send them proof that I have a license and ask for a replacement, not sure if this is possible, was just wondering. If anyone else could help that would be great.

Yes, it's definitely possible - here's my standard spiel on the subject...

There *may* be an alternative solution though, if you are patient and persistent.
Attempt Telephone Activation, and speak to an operator - they will tell you that your current Key is blocked (they should then ask for confirmation of your Product Key). Explain to them your problem, that you need to change the Key to the one on your sticker, but that the sticker is unreadable (could they please supply a replacement Key?). Hopefully they will ask for documentary proof of the sticker, in the form of an email with a picture of the affected sticker - and you can proceed from there.
Sometimes it takes two or three calls before you get an operator who actually knows and uses this procedure - but I know that it can and does happen.

telephone activation (operator calls)
Click on the Start button
in the Search box, type
SLUI 4
and hit the Enter key
follow the instructions, but when asked which service you require by the telephone ansafone, do NOT reply - this should force an operator to respond, who can deal with you