You can add any amount of collateral to your Wirex credit 
 
To add collateral, simply add funds to your crypto account and you will be able to send funds from your crypto account to the collateral amount. 

You can add collateral from one of the crypto accounts: ETH, WXT, BTC, YFI, MKR, AAVE, UNI, COMP, LINK, 1INCH, SOL, AVAX, MATIC, DOT, ALGO, ADA, TRX, WXT, XRP, XLM, LTC, DOGE, SHIBA, AXS, APE.

In order to add collateral, click on the Wirex Credit account you wish to fund and hit Add Collateral.