Appliances over 10 years old break down. Generally they have specific parts and electronic control system. If a circuit board is faulty these can be expensive to replace, these can sometimes be repaired be sent to a specialist repair that may or may not be able to repair the electronic circuit board. Repairs can take, a week or several weeks and this can be very difficult emotionally, to cope without. The electronics and design is over 10 years old. There is no guarantee that another problem will not occur.
Do you pay for an expensive repair on an appliance that is older than the life it was designed for?
Do you install a new system, more efficient, updated technology with a new warranty generally 3-5 years?
Your repairer cannot make the decision for you, they cannot be held responsible for the decision you made, especially if the repair cost more than a new system would to install.