Replacement SIM activation

New to Smarty & always have had difficulty activating Smarty SIM for some reason. I’ve just received a replacement SIM and exact same problem. And finding there little help or support from Smarty to rectify the problem. 
Also have a GIFFGAFF SIM activation is straight forward so struggling to understand why it is so easy with one provider and so difficult with another. 
Any help/support would be very much appreciated. 
Currently having to switch between SIM’s to see if I’ve received a help message to sort the problem; no such look and now closed until the morning🙈