Since things have come to this stage, my advice will be to change PDI.
On a side note: I'm not sure how come the communication (in terms of time/ date of slot booking) between the two of you can go wrong.
1. For me: end of lesson, without fail, i will take out my card and book my next few lessons with him. The card is important not just for him to indicate the timing and date but most importantly, he has to sign to acknowlege that he received my payment.
2. To know what are the slots available, he will open his diary/ appointment book. And I will definitely look at it and choose the better timing/ dates. And I will watch him fill up my name in the correct time slot and date. And obviously, i will also check my card to ensure that it tallies.
yes, definitely changing PDI, no doubt.
and i don't peek/look at his diary, don't have this habit. besides, i have DOUBLE-confirm, repeating the date & time each time I book my lesson. he did not request the card from me probably becos i have not paid him yet. he said i could do a bank transfer.
before doing the bank transfer, i again, double-confirm by calling him up, making sure the 6pm slot has NOT been taken up. at the same time, i made appointment for another 3 slots for the next 2 weeks at my usual 4pm slot.
i think this is where he could have confused himself, by indicating all 4 slots at 4pm!! if not, i really duno why he wrote mine as 4pm instead of 6pm for today's lesson.
or, he might have given up my slot to someone who paid him before i made transfer. in any case, i did confirm whether 6pm slot is still vacant before i paid. so where went wrong??!!
i'm pissed becos i'm a serious learner. i was NEVER late for any of my previous lessons. and i paid in advance for 3 more lessons! why can't he compromise? why does he spoke in such STERN tone that i WASTED his time & fees will be FORFEITED no matter what! there's also a possibility that he wrote wrongly right?? he's not a saint!
i had to wait 2 weeks plus for my 1st lesson. + another 2 weeks in between my lessons becos he is always fully booked. i could have progress so much more else where but i waited! talk about who is wasting whose time here!