I don't use eParcel, so I can't really provide much insight, though I would normally expect to receive advice if on a contract and prices were changing (though anecdotally I believe this doesn't always happen, so probably worth getting in touch with someone and finding out what's going on).

I do know AP are continually looking for ways to increase profits either by increasing prices, introducing new charges, or phasing out services. (eg I know from other sellers who do use eParcel that soon, the default for signature on delivery packages will actually be 'signature on delivery with authority to leave', and if you don't want your packages to have this, you have to alter your account settings - last I checked, you needed to contact AP to find out how ).