NEC TSC: Are the provisions of Clause 91.2 dependent on following the procedure as listed on Clause 90.1 or can termination be effected directly.

Two aspects to this question based on NEC 3 Term Service Contract;

1. The Employer terminates citing R11 , substantial failure to perform as the reason under Clause 91.2. Before  the termination a  default notice is clearly required from Service Manager. On the lapse of the 4 weeks  it is implied that the Service Manager advises the Employer of the status of  contractor's default. The employer can then make up his mind if the default still exists and proceed with the termination. Assuming the Employer decides to proceed with the termination, does he then need to  notify the Service Manager and the other party giving details of his reasons for termination as provided for under clause 90.1? Or can termination be carried out under 91.2 directly?

2. Under the Data for secondary option clauses Z is a statement that;
 'The Contractor will not be granted four weeks duration to put the default right  as per core clause 91.2 if the Contractor, as per first bullet,''substantially fails to provide the service(R11)''.
Will a notice by the Service Manager still be required under this changed scenario to the Contractor? Will the termination be  effected directly under 91.2 or will the procedure under 90.1 be followed?