Dear DC

Putting aside the assumption of bullying because of previous track record.

There was a leak of water from your flat into the flat below.

Do you in principle  think it reasonable for this repair to be done quickly to prevent more damage to the flats no matter who occupies them?

An equitable solution could be is find out what your plumbers hourly rate is compared to the managers plumber and also check to see if the materials used was charged to you at a fair price. Then present these figures to Bella if there is a difference and pay that amount you have calculated if you had used your own plumber if you are liable for the leak.

Kind regards

Roberta