Couple of points:
Contractor should not be acting upon a verbal instruction and you should not be expecting them to. Clause 13.1 confirms that an instruction has to be in a form that can be read, copied AND recorded.
Compensation events under option B are only payable once they have been Implemented - i.e. agreed in terms of time and cost. They only get added to the BofQ once they are implemented.
So actions would appear to be:
1)Give the initial instruction in writing and under 61.1 state it is a CE and request the quote.
2) Contractor gives quote and you assess. If you agree it is implemented otherwise ask them to re-quote or you make your own assessment at which point it is agreed in terms of time and cost
3) the Implemented CE gets added to the BofQ and the Contractor is paid for the item when it is completed.