There’s no reason for them to hold your cash back, so remember it’s covid so staff might be low or not the usual staff dealing with it so are being super careful, if it’s a casino with UK and Malta watching them it’s juts a matter of time, unless there is something wrong, (using somebody else’s money or not your account for example) but the “know your customer” is legit and has to be done, mine took a few hours some take longer, covid isn’t helping… but £150 isn’t a amount that would cause major grief . You can suggest they deal with it quickly or out line the issues that is causing grief or you will forward it to gambling commission, they won’t want that… so try that …but losing your shit with them won’t speed anything up so keep a cool head and just try the above suggestion….
