weatherproofing damaged external facia tiles

[connjam]

the exterior of my house is brick around the bottom half but the top half is studded wall covered in faux brick tiles which are attached by metal clips. some of these are damaged and either broken yet still held in position or have pieces broken away exposing the cavity between brick tiles and stud. i cannot locate a supplier for these tiles so need advice as to how i can weatherproof the exposed cavity.