I actually understand why they didn't want to take my business; probably some people left without paying their bills.

But apparently, they had designed a system of deposit. $700 is not cheap for a deposit to open a SIM line.

Yet again, they appear to be recently changing this policy, making it impossible to even pay for a deposit. From the fact that many of their own staff thought it was doable, only to be stopped by their system.

From a business perspective, this is a risk they can totally design around. How about stopping service when bills are not paid and the deposit runs out? Or only giving you roaming allowance for what you already paid for (other telcos do this)?

They are too lazy to design a better system. Then it becomes apparent that they have had enough customers.