Promised progression in Job, but have seen none. Need it now

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I have been a chef for over 5 years, and through a lot of hard work and extra hours I've managed to become a Head Chef. I recently (October 2015) got approached by a company to become their Head Chef. They are a new company, and have been around for just over a year, so are learning as they go. They are very very profitable and are opening up two more shops this year. I joined the company because I saw a lot of promise, and invested my time and skills in the company with the promise that I will become the manager of every additional kitchen opening up.
I started on a measly £7.00p/h and was promised an increase as soon as I proved I could do what I said I could. I have yet to receive any increase although querying it. My responsibilities have increased, I now take care of 90% of orders, menu design, pricing, weekly special design and pricing, additional prep work at home and supplier relations.
I am patiently waiting any word from them, as I am in the midst of trying to move out with my Girlfriend. We need to move out by June and are struggling to be taken seriously by any estate agents as I'm only on £12,000 ish a year.
Do I query my wage with my employers? Do you think they're playing me? (Although if I leave, they cannot run the kitchen by themselves, as they have no other chefs and any other staff that can make the food I do) Do you think I should start to seek either additional work, or a new job?
The problem is, with the company growing at such a speed, and I pull out now because I'm struggling, I will lose the opportunity to become a high ranking employee within a business I can see becoming a country wide name.
Thanks for reading, any help would be great!