They transferred £2000 out of my account randomly one day with no cause or explanation when there was £118 available in it. The next day they froze the account and a specific contact at HSBC forced me to make a repayment arrangement for the money. I refused and opened a dispute and it took me 14 months to get it back and all fees incurred for entering an unarranged overdraft. It ruined my credit rating for 3 years. Every contact I made with them was handled by someone utterly incompetent or disinterested in solving the problem even when I involved a solicitor.
Never an apology, never an explanation, never a true resolution.
NEVER work with HSBC. ALWAYS keep your finances distributed between multiple accounts.
With Santander mostly now who so far, touch wood, have succeeded in not fucking anything up. Halifax as a backup.