Shipping at Checkout - Rules where country = Australia

i) The shipping rate will not change on the number of pieces shipped. 

ii) Maximum order is for 10 pieces of any item 

iii) Note : Depending on the postcode of the DELIVERY there will be 6 shipping zones and corresponding rates.

iv) Note : Australia Postcodes are always 4 digits, numeric

v) Note : Postcodes are allowed to start with "0" 

vii) Lookup the postcode in the attached tnt_zones.sql .... this will allow you to find the region code (SYD, ACT, NSW, BNE, QLS, QLN, QLC, MEL, VIC, TAS, ADL, SA, DWN, NT, PTH, WAS, WAN). If the query returns NULL then the postcode was invalid. (N.B. invalid postcodes should never be possible)

viii) These zones easily correspond now to the following zones for fixed rate shipping charges :-

ZONE 1 = $ 12.95 (SYD, ACT)
ZONE 2 = $14.95 (NSW, BNE, MEL)
ZONE 3 = $ 17.95 (VIC, TAS, ADL)
ZONE 4 = $ 22.95 (QLS, SA)
ZONE 5 = $24.95 (QLN, QLC, PTH)
ZONE 6 = $31.95 (DWN, NT, WAS, WAN)

I will need to be able to modify these shipping rates from time to time.

Shipping to be disabled for the time being to any other country than Australia.

PostCodes

When user opens their account and enters their address OR a new shipping address AND where country = Australia, validation must be done that (a) value of postcode = 4 digits numeric, (b) exists in tnt_zones.sql and "NULL"

Country to be temporarily fixed to be Australia - no other choices possible (but must be temporary as in 2 or 3 months I will start shipping overseas)