Frostbite, your contract is indeed with Makro and they are responsible for honouring your warranty agreement. If a fault develops within six months then they should do something pdq - like giving you an instant refund or replacement. If the six month period is exceeded, but you are still within the warranty period (1 year?), then the supplier must still honour the warranty agreement, but the repair may take longer (i.e. they return it to the manufacturer.) Under these circumstances, you may consider doing this yourself to save time, but in doing so you may absolve Makro from any further responsibility for effecting further warranty repairs.
P.P.