We would rather hear a complaint than lose a customer quietly.
HOW TO RAISE IT
Open a ticket describing what happened, when, which service was involved, and what outcome you are looking for. Include ticket or invoice references where relevant.
WHAT HELPS
Specifics. "The migration was scheduled for Tuesday and completed on Friday with no updates in between" can be investigated. "Your service is poor" cannot. Dates and references.
A clear statement of what you want: an explanation, a correction, a refund, or a change in how something is handled.
WHAT HAPPENS
We review the account history, ticket records and relevant logs, and reply with what we find. Where we were wrong we say so and put it right. Where we were not, we explain why with reference to the records rather than simply asserting it.
IF YOU ARE NOT SATISFIED
Say so in the same ticket and ask for it to be reviewed by a manager. Escalating within the thread is faster than starting elsewhere.
POSITIVE FEEDBACK
Also welcome, and genuinely useful. Knowing what worked tells us what to keep doing.