how to answer petition sued by midland funding represented by love beale nixon in oklahoma

My husband was served a petition last week. I understand that i immediately need to answer to avoid default judgment, I’m just not sure I’m smart enough to do it properly.

Honestly, the petition is quite short it reads:

1) Unless you, within 30 days after receipt of this notice dispute the validity of the debt, or any portion thereof, we will assume the debt to be valid. If you notify this law firm, Love, Beal & Nixon in writing within the 30 day period, that the debt is disputed our law frim will obtain verification of the debt and mail a copy of the verification to you. ....and provide you the name and address of the original creditor.

2)HSBC Bank Nevada provided credit to the defendant on a written credit card account with account number XXXX. The indebtness arising therefrom has been duly assigned to Midland Funding, Plaintiff herein. The defendant defaulted on the obligations required under the contract.

3) The defendant remains indebted to the plaintiff in the amount of $1900 inclusive of credits, adjustments, interest, and fees, if applicable.

It then prays for judgment for $1900 with interest, court costs and attorneys fees.

How do i determine if the SOL is exceeded? A local atty states on her website that the OK SOL is

Account Stated"-the contract is "implied" because of your use of the card and your agreement to the contractual terms, even if there is not a written contract signed by both paries.  THE STATUE OF LIMITATIONS IS 36 MONTHS FROM THE DATE OF YOUR LAST PAYMENT ON OR USE OF THE CARD.

"Written Contract"-the contract is signed by both parties and the terms of the contract are apparent on its face.  THE STATUE OF LIMITATIONS IS 5 YEARS FROM THE DATE OF YOUR LAST PAYMENT ON OR THE USE OF THE CARD.

The petition specifically says written but how do i verify this?  According to my husbands experian credit report the last payment made to HSBC was May 2008. So if indeed it is a written contract SOL is not up but if it was an implied contract it is.

How do i make them prove they have a right to collect this money?

Midland funding is one of the bottom feeding bad debt buyers who harass people and I would love to beat them. 

I have no idea how to answer this petition, what steps to take next. We are a single income family with three children, I cannot afford an attorney. Any advice is much appreciated.