Proceedings before a Labour Court in respect of dispute falling under caluse (a) of Paragraph A of sub section (1) of Section 78 shall be commenced on an application made by any of the parties to the dispute. (2) * * * (3) An application in respect of a dispute falling under clause (a) of paragraph A of sub section (1) of section 78 shall be made (a) if it is a dispute falling under sub clause (i) or (ii) of the said clause, within three months of the arising of the dispute;" 823 It will be seen on a combined reading of these provisions that an application to the Labour Court under section 79(1) in respect of a dispute falling under section 78(1) (A) (a) (i) must be made within three months of the arising of the dispute and the dispute would be deemed to have arisen if, within a period of 15 days from the receipt of the letter of approach under section 42, sub section