Bulgarian invoice dispute

We need advice on whether we have to pay a management fee invoice for our villa in bulgaria.

We paid a management fee before we signed our notary, but in our contract it says we didnt have to pay until after our notary was signed.

Now they are asking for more money for the 2009/2010 management fee, but we want the money carried forward from the invoice we paid before our notary was signed to pay for this.

They say they wont do this and have even taken money from our villa account without our permission to pay part of this invoice.

We have rentals booked for our villa, and they have flights booked, but the management say that we cant rent our villa out without paying the invoice, even though they confirmed our bookings and said they were fine.

We are worried that our rental customers will sue us for their flights and alternative accomodation, if they wont allow them in to our villa.

Looking for sdome advice ASAP.

Thanks