Gaming keyboard - Takealot disappointment

My son paid a lot of money for a gaming keyboard. While it was still under guarantee, it stopped working. He asked for a replacement but Takealot gave him a refund and told him to buy a new one. He searched for the same one and saw that they still had the same keyboards in stock. He questioned it and they said "you got a credit".

Now this is ******* because the prices have gone up so they want him to pay in the extra to replace this keyboard which is still under guarantee

I am most disappointed as we have purchased a lot over the years from Takealot and to suddenly bear the brunt of the costs when the keyboard is still covered, is really unfair