If there is cord/wire damage then the only people to advise or repair are professional tyre repair specialists, few around and unless the tyre is new a major repair might not be cost effective.
Take it to a tyre sales place, they'll tell you it's scrap and sell you a new tyre, they are not qualified or have the knowledge to repair a tyre properly.
Alternatively take it to a tyre repair workshop who will either repair it if possible or tell you it's scrap and the reason why.
I'm just a bit suspicious about tyre dealers. About a year ago I went to one who told me that my tyre couldn't be repaired and so I bought a new one.
I went back there about a month later after I kerbed another tyre. I was offered a used tyre which looked suspiciously like my old one - it even had silver over-sprayed paint on it!
In the past I have always used the local tyre dealers Savoy.They have always being honest with me.If they could repaire the tyre they would so no complaints.If a tyre has side damage not often it can be repaired.Nail in the middle or glass can be done.Unless there is a tyrefitter here who knows different.
Remember these second hand tyre places get there stock from the lads who work at the national outlets the fast fit places, It used to be £5.00 per tyre sold to them i took about 8x a week in back in 1994 so the prices may have gone up a little.
Id tell you it can't be repaired on the shoulder you would buy a new one id fix it when you left and flog it to the garage, all this was because the garages paid poor wages.
You can get repair kits to repair them yourself, I do this these days, a special tool squashes a plug which is then inserted and released inside the hole with glue. Motorcyclists do this and it is common in other countries.
BSAU159f:1997 is the British Standard on tyre repairs.
It seperates repairs into 'minor' and 'major'.
KwitFit et al can do minor repairs.
Specialised tyre services can perform vulcanised repairs on major areas (had one done on an almost new tyre with a screw in the shoulder - KwikFit chap actually told me it was repairable, just not by them.
If the tyre has been driven deflated and the carcass is goosed, or there is mangling of the wires by the offending screw you'll be advised to get a new tyre.