Lenovo — Unauthorized gpu replacement and battery issues after paid motherboard replacement

I paid full amount for a motherboard replacement at an authorized Lenovo service center for my out-of-warranty laptop (original config: i5-12450H, RTX 2050, 16GB RAM, 512GB SSD).

However, without my permission, the service center replaced the GPU with an RTX 4060, which is incompatible with the existing battery and charger. This has caused:

Fast battery drain

Poor performance on battery power

When I raised this issue, the service center refused to fix it and shockingly offered to take back the new motherboard and return my old, damaged one — despite me paying in full for a working replacement.

Lenovo customer support also told me they cannot help and that I have to deal with the service center directly — even though the fault is clearly theirs.

I am requesting:

A compatible battery and charger to support RTX 4060, OR

Revert the laptop to its original specs with proper working parts, OR

A full refund for the amount paid and compensation.

This kind o[censored]nauthorized modification and lack of support from Lenovo is unacceptable. I have full documentation including invoice and system specs before/after the repair.

Please help resolve this issue urgently.