If you've had 3 water pumps and tried seals .. it only means one thing, that i can think of, that there is a crack in the cylinder block from which the recess for the water pump is machined into ..to the left in the picture.
https://i.ebayimg.com/images/g/PNgAAeSw ... l1600.webp or there is corrosion in the part the seals mates up to ... can be fixed with dremel with wire brush and application of JB weld in the pits and sanding.. someone has to be well practiced and know what they are doing
other than that ..
The only thing you've got going for you is that because of the amount of these engines getting trashed, because of the wetbelt failures .. there are plenty of cheap used blocks on ebay from £180 ish upwards .. most under £300 .. ignore the £10.71 ones.
What's not on your side is that you'll have to pay someone to take the old one out and swap the parts over .. complete rebuild and fit.
OR
The only other quick maybe permanent fix is this stuff
"Steel Seal" ive heard good reports about it .. you add it to the coolant.
That's my best guess
There have been no reports of this engine ever doing what you say it's doing. Mech over-tightened bolt .. and cracked the housing maybe . or corrosion as mentioned.
and .. bad mech not know what he's doing
how to
and another clue
he said he had to clobber the pump to get it out -- damage from that to the block on yours ???
https://www.youtube.com/watch?v=jaQsXVkaE4Yall the best.mark