They are very reasonable on the phone but for sure change your address as they are very archaic when it comes to settlement and payments.
I had a small dispute with them and to avoid penalties I had to first pay extra over the tax years 2017-2019. After the dispute was settled they concluded I had to pay a little extra for one tax year but would receive a lot more back for the other two taxyears (more then I had paid extra initially). So I asked them to settle the three taxyears and repay my tax in one go. That was not possible ofcourse. I had to pay extra the one tax year (let’s say 50.000 HKD) and at the same time they refunded the other two tax years (let’s say 100.000 HKD). Stupid but true. So to avoid penalties I paid the 50.000 HKD electronically and then received two checks for 100.000 HKD (what an outdated system) one month later in Europe, only to send them back by returning post to a friend in HK to deposit them in my HSBC account.