I was employed as a mortgage advisor up until 2yrs ago when

Hi
I was employed as a mortgage advisor up until 2yrs ago when I decided to go self employed. I joined a Network called the Mortgage Advice Bureau (MAB). For a share of my income they look after my compliance, training, software licences etc. They are also tasked with finding lead sources for individuals.MAB put me into contact with a company called The Property Group. Based on a verbal agreement that I would receive at least 40 leads pcm from between 5 of the estate agents in the group I estimated I would earn £65k + pa. (The estate agents were called Mayfair, Simon Williams Mayfair and Gary Berrymans).It was also agreed that staff members would be targeted in order to support this figure. As a result, to be tax efficient, I set up a Ltd Company called Inglebrook Mortgages. In addition to this verbal agreement their was the expectation that I would agree to an Introducer Agreement which was drawn up between MAB and the Property Group in 2015. The agreement states that for any leads that complete into mortgages, I would pay the sum of £250 to The Property Group (£100 to go to the agent who passed on the lead and £150 to The Property Group). I never received close to 40 leads a month whilst working with The Property Group and asked for support in paying the sales negotiators from The Property Group to keep them happy until such time my new business had grown enough to pay The Property Group in full for the small amount of leads that had converted into mortgages, this was rejected but I was given an additional 4 branches of Mayfair estate agents to look after(I never converted a single lead from these additional agents as the majority of their clients were cash buyers). In addition, the Director with whom this arrangement was made was let go by The Property Group for reasons unknown to me. Following this, I met with the new director 02/04/2019 and raised my concerns about low leads and trying to keep agents happy. I again asked for support but was told no and that The Property Centre would not be working with me anymore. This was followed up with an email to all staff in the agents I was working with to advise not to pass anymore leads to me.That was the last I heard from them until I received an invoice for £1000 for 4 cases that had completed.My arguments are that the in the Introducer Agreement the introducer is named as Mayfair (holding company is The Property Group) therefore 2 of the cases I was being invoiced for did not count as they came from Gary Berrymans and Simon Williams. In addition, point 11 on the agreement states either party can end the agreement at any time by giving notice in writing. I never received any notice so they have breached the terms.I am in the process of closing my Ltd company down and continuing on a sole trader basis.Any advice would be really appreciated.