Shower drain leak

In the past two years my shower has leaked twice. My initial plumber seems to have drilled a drainage hole slightly off centre but within the indentation which my second plumber believes is the reason for the problem. This plumber thinks i should replace the entire unit which I believe is an overkill. I have included a pic to clear any doubts. I would appreciate any input into this problem. Thanks.

Personaly I have never seen a shower drain that had to be drilled out. They all come predrilled. It is off center but I would think that if the trap and drain are plumb and the shower base does not flex when you are taking a shower it shouldn't leak. That said if all is right and it does leak again you may have to change out the shower.

Thanks for responding to my post. Would it be all right to use mortar to secure the shower if the drain and trap is well connected?

If you are referring to underneath to give it support, yes, this is fine. The mortar doesn't really need to adhere it to the floor, but support it.