Cost of a new internet cable (??)

Goodmorning.
My O2 modem was not working so I asked O2 to send me a technician at home.

The guy came and wanted me to pay 22 euros for a new internet cable. Please note: he wanted the money in cash and he gave me no recipe. It seemed shady to me, but I work in homeoffice and I really needed the Wifi to work, and the guy told me that this was the only way to get internet working, otherwise I had to get a new modem but I was supposed to wait some days, so I gave him the money.

I called the O2 hotline to talk about this, they kept me on the phone for 25 minutes and they made me talk with 3 different operators, then the last one just said "sorry I have to check something" and closed the call. Calling the hotline, having to talk with the AI at the beginning and then being bounced from one operator to the other with long waiting times is really stressful.

I want to know if it is normal that O2 wants money to repair/replace an internet cable and if it is normal that a O2 technician could ask money for this, wanting it in cash and giving no recipe.

None of the above seems fine/normal/legal to me.