So you need to contact Gamdon, explain your withdrawal has been stuck for 3 weeks, explain that given the state of the mempool at the moment it is likely going to be stuck for many more weeks, and ask them to replace it with a transaction paying a more appropriate fee.

Additionally, you could try asking them to send the coins to a different address, one which comes from a real bitcoin wallet such as Electrum which would allow you to use CPFP to avoid this situation in the first place.