Help with string inverter problem

PotentialEnergy

Last Sunday I was mystified as the readings seemed to edge back to normal. Could it be grid settings I wondered. I still wanted the installer to come and despite numerous calls never had the phone answered or calls returned. Then at 840PM on Thu eve I get a call - Oh is it OK if they turn up tmrw between 2-4PM. I said fine. Then 8:30 am Fri I get a call from the workmen - a job we were scheduled to do has been cancelled. Can we come in about 45mins? Yes I said as I was luckily for them taking the day off.
Well, they turned up and almost immediately found the problem. They switched off the inverter and it didn't seem to start up counting new energy. When they went up to the roof they found some pigeons had affected a connector which had then fused. That was why the string had stopped working! Loose connection due to pigeon nest. They fixed it and hey presto, I've generated the most energy in a day since 28th June - the day before the problem came to light.
So, if a proper job had been done in mid July all this hassle could have been avoided.
I've lost £200 FiT payment, had a load of my time wasted, troubled SMA and paid them £163 needlessly. The best they offer me is £250 off their apparent £650 charge for doing mesh fitting to stop pigeons/jackdaws nesting.
I've got 2 other quotes so far which both carry a 10 year warranty. One is £400 uses mesh and plastic pads on the underside. They say they are contracted by many other firms.
The other is £870 but a thorough
1: Clean the tops of the solar panels to remove the bird waste.
2: Remove all the birds and their nests from under the panels.
3: Carry out a full biocide treatment under the panels.
4: Clean and remove all debris from the gutters.
5: Supply and install high grade galvanised metal mesh to the outside edge of the solar panels.
The mesh will be custom cut on site to fit the panels. The mesh will be attached to the legs/bracket using wire.

Any thoughts?