Come on, give us more details...
1. Engine (which one)?
2. Why do you think you need a "fix"? What's the problem? Car misbehaves, error codes?
And. Literally fix (repair) or swap, replacement?
There is not much to "fix" really. Spare parts are probably not available.
If throttle body is bad, replace it (easy, kid/teenager can do this with basic tools). They don't fail that often. So, you can buy cheap used one on eBay, low risk (99% chance, it will be fine). Swap it, or repair current one using another used throttle as a donor.
Example (disassembly), engine 1,4 8V:
https://www.fiatforum.com/grande-pu...-body-disassembly-porting-testing-1-4-8v.html
As for price, eBay/Google it yourself! Forum is not a "search-engine" (you throw a question and answer magically pops out). Two different services.