The usual problem with recieving anything once you have made an instant payment to them

I really wish there was an alternative provider to use in order to access the site I do there is always some kind of a problem once you have made a payment to them it feels like they try and hold onto the money for as long as possible perhaps they recieving interest on these funds ???definitely seems like it . I carry the cost of the instant payment the funds leave my account but according to them they don't have it and it takes up to a week to recieve goods paid for