Is this normal practise ? No, repairs to any component under warranty should not involve changes to any others, particularly where it degrades the specification.
Who to contact ? When I had a delivery problem with Dell, I used this e-mail address [email protected] quoting all relevant transaction details, original order number, Service tag No and the tracking number. The whole thing was handled quite effectively by the Indian call centre. Do note any names on response messages and limit correspondence to the same person though.
You could also drop their complaints people a line click here