Just take copies of her Thai ID and blue house book signed by her at the bottom in blue ink. That's all you need from her. Then the standard copies from your passport and a copy of the contract. These copies signed by you at the bottom in blue ink. Then fill out the TM30 (both pages). Then visit your immigration office where ever it is located.
The money required must be in a Thai bank account 2 months prior to the day you apply for a 12 months extension at the local immigration office. That's the official requirement.
I've been with Pacific Cross for years. A very reliable and trustworthy company based in Bangkok.They have always been in the top when it comes to reviews. They have loads of different priceworthy plans. Google them. A piece of advice, don't use a broker.