Seller refusing my order, cannot contact. Have no idea why, as I have previously purchased from the.

[sandypebbles]

Nobody can make them sell to you if you choose not to

How do you mean they refuse your order? do you get a message on the screen?

Have you any unpaid items since you last bought from them?

Are they overseas and stopped shipping internationally since you bought from them?

Nobody here can offer much in the way of suggestions, especially with only an incomplete comment in the heading and nothing else

[papermoon.lady]

If you cannot place an order AND you cannot contact them either, as your title says, they might have blocked you - for whatever reason. As Sandy said, if they are overseas they might have stopped posting to Australia.

[papermoon.lady]

Did you leave positive fb for them in the past? Was there any kind of problem, like delays, or something that didn't meet your expectations?

[jellybirddesigns]

If you've left either a negative or a neutral for a seller, you may find yourself blocked.

You may also find yourself blocked from various sellers for any number of reasons, such as asking questions when the information is in the listing, asking too many questions in general, tone of messages to sellers. 

Could be anything really.

Without knowing exactly what message you are getting when trying to purchase, it's hard to guess.