Orange Belgium invoiced me €50 for unpaid bill even though the guy at the shop couldn't figure out how to install the eSIM on my phone and said he'd cancel the contract. What do I do? They say I have 14 days to pay before their 'amicable' warning becomes a judicial matter

Context:
- In November 2025 I tried opening an eSIM contract with Orange
- I signed the contract opening the phone plan but when we tried to install the eSIM on my phone at the shop, it didn't work (at the shop), so I went for another provider.
- Amongst all my spam emails, turns out they were sending me unpaid invoices
- Today they sent me their last warning which they said would turn into a legal matter
- When I called them, they said nothing would be done seeing as they have no proof I cancelled the contract
- I literally never used the number, or had access to any of their services.