2.75 an hour is shit money, however they also have given them a roof over their heads!! She could always go and get another job if she wants to earn more money. Perhaps they are trying to build up the business. I do all my DPs work for him, ALL of his admin, his accounts, his marketing, make his difficult phone calls etc - for the princely sum of Sweet FA per hour!!
Im not saying i don't sympathise, i just wonder if the OP needs to post more information if she wants more sympathy.
There are two very stark choices, shut up and be grateful that her parents have put her up and have promised the £150K (which is a fortune but the OP is whining that it wont buy them a four bedroom house ) or move out, get a job and get a mortgage, you know, like the rest of us have to.
That is the stark reality and very simplified. I can read between the lines that the OP is obviously feeling trapped by her parents, i totally understand that, which is all the more reason why i think she should make her own way. I also dont know why the OP had to sell her original house, was it just the dream of mortgage free living sold by those stupid property programs (she did say grand designs was their bible). Maybe it is time for a reality check.
My advice, move out, not in a strop, you want to maintain the relationship with your parents. Set yourselves up, then when and if they move and give you the £150K you will be in a really great position, better than if they simply give you the money. Maybe they want to feel like you are contributing yourself. The 30K im taking, comes from the sale of the original house, which you wouldnt have had if you couldnt move in with your parents. So legally thats a difficult one i guess.
I think the OP has things out of perspective and i totally understand her reaction, but i think for the sake of everyones relationship they need to step back,.