What are the most common faults with the Audi A3's transmission system?

I recently purchased a used Audi A3 and have been experiencing issues with the transmission. It seems to struggle when shifting gears and occasionally makes a strange noise. What could be causing this and what steps should I take to fix it?

The most common issue with the Audi A3's transmission is a faulty mechatronic unit. This is responsible for controlling the gear shifting and can be a costly repair. It's best to have it diagnosed by a professional and consider contacting Audi for possible reimbursement.