Point of taxation rules in gst & service tax

There is a difference in POT rules of service tax and GST.

In Service tax ,
POT rules ,POT will be the earliest of the following :

1. Date of Issue of Invoice if the same is issue within 30 days
2. Date of Completion of Service if Invoice is not issue within 30 days
3.Date of Payment

However, In GST ,
Point of Supply of Service will be the earliest of the following :

1. Date of Issue of Invoice
2. Date.of receipt of Payment

In Gst , POT rules are simple not complex like POT rules in current tax regime. In Current Tax regime , If invoice is not issue within 30 days. Then Date of Completion will become date of issue and Accordingly POT shall be determined but in GST there is no such provision . It is pretty much simple and clear .So lets take an example on this Difference .

Assuming that GST will be applicable from 1 July 2017.

Suppose Date of Completion : 30 june 2017
Date of Payment : 14 July 2017
Date of Invoice. : 1 Aug 2017
Then as per service tax POT rules , Point of Taxation will be Date of Completion of service i.e 30 June 2017
But As per GST , Place of Supply Rules , POT will date of Payment i.e 14 July 2017

So , My question is that whether on this transaction GST will levied or Service tax will be levied.