It seems you booked a (P) class ticket. (P) fares are widely documented as not including lounge access, including it being very clearly stated at the time of fare selection and booking. So if you then choose to go ahead and buy (P) anyway, you are relying solely on either any oneworld status you may have, or paying as you go. Subsequently buying a one off pass for a specific lounge at one airport does not mean you have bought passes for lounges operated by other companies at every other airport en route. You would need to buy separately, or to pay the fare difference to upgrade your ticket to a higher fare bucket that did include lounge access for that.

QR Silver is oneworld ruby. Usually OWR wouldn't get you in to any lounges anywhere so it probably shouldn't be a surprise you can't guest people in for free, even though QR do offer lounge access at DOH for their silver members (ie. more than other oneworld members offer to their OWR members). You don’t say which lounge you paid for at DOH, possibly one of the arrivals lounges if you could not get to it from airside. Alternatively you could have paid on the door for a guest at the Silver lounge, I think it's QAR 300. Or you could have used one of the 2 guest passes silver members receive per year to take a guest in to the silver lounge with you, both for free.

And you wanted to change your destination mid-journey? I can't see many (if any) airlines allowing this, and particularly not for free. Why did you not just book to DXB in the first place for the shorter connection, was the SHJ ticket much cheaper?

Criticism is fair where it's due, but taking advantage of a cheap (P) fare and then expecting what you have suggested does not really sound shambolic on the airline's part, sorry.