Faulty product and no after sales service

Ordered a chair through Leroy Merlin Market place. Whilst delivery of the item was swift, i immediately logged a request for the chair to be replaced as the mechanism which allows the chair to change height is faulty.

I have called and emailed repeatedly over a week and still do not know when the replacement chair will be delivered and faulty chair collected.

No communication or progress notification from Leroy Merlin is disgraceful.