“…However, the focus was mainly put on the number of waiting customers (see e.g. [5], [6], [7], [8], [9], [10], [11], [12], [13], [14], [15], [16]), whereas the waiting time of customers, also called customer delay, has attracted very few attention, especially in the case of batch arrivals. In [17], [18] and [19] we have computed the probability generating function (PGF) of the customer delay in distinct discrete-time queueing models with batch arrivals and batch service.…”