howdy do. just saw your question. i'm not familiar with petsmarts' products, but i'm sure that most of the lines carry a conditioner or two. depending on how long the coat is at this point and how often you bathe her at home between groomings, i'd suggest either a product that is a leave-in conditioner (after a bath and while she's still wet, before blow-drying) or between baths on a dry coat, you could use a 'tangle-free' spray. I know that 'Perfect Coat' makes the latter in a clear spray that you can use on either a dry or wet coat. I'ts sorta like Johnson& Johnson's product that we use on our own hair, "No More Tangles".
If you comb through her coat every day and get to the skin when combing, that should do it. Mats come into play when you only comb through the top parts of the coat and don't get down to the skin. Faces get knotted easily, I know. If you use a brush, be sure that you use a pin type that is long enough to reach to the skin. you can brush against the coat too. most dogs like that better anyway...you may make more headway that way getting to the skin. as for the face, using your comb, instead of just combing through the face, try to turn the comb lengthwise to the face using the wide-spaced end and sorta 'knife' it through a tangle with just one tooth to separate the hairs. once you've done that you should be able to turn the comb back and comb through it with the wide side. then comb through it with the narrow teeth. okay?