Any suggestions for cleaning a glass shower stall?

I've tried comet, scrubbing bubbles, CLR and anything on the label that says lime or hard water stains removal. Nothing seems to get that off. There is just this “etched” look to the glass. Any suggestions? I was thinking of just hiring a maid service to use it as I assume they would use more commercial strength chemicals but I wanted to give it one last go before I totally give up. Thanks!