Thats a bit of a rough call mate, here is a guy thats willing to get in and give it a go and your bascially calling him a numpty for stripping a bolt..
I have stripped and broken plenty of nuts, bolts, screws in my days , its part n parcel of playing with old cars, especially with limited tools at your disposal, and i bet if you ask any mechanic or engineer they will have stripped a bolt or two in their days..
I sent my car to the dealership to get serviced and they stripped the radiator drain plug causing it to leak and overheat my car, do you think i should give these knobs my hard-earned?..
To OP, i dont know how to help you sorry i usually call a guy to come fix me messed up bolts...I just dont have the tools to do it and he makes it look so easy cause he has cool tools that can only be bought on the black market..