How to chase a repair that's overdue

Hi [Company name],

Checking in on [item], reference [reference number]. It was due back on [date promised] and I haven't heard anything since. Could you give me a real update, and a new date if the original one's no longer accurate?

Thanks,
[Your name]

Hi [Company name],

Hope the delay is a sign you're just backed up rather than anything worse. [item], reference [reference number], was due on [date promised] and I haven't had an update since. No rush on an apology, just let me know honestly where things stand and roughly when I can expect it back.

Thanks,
[Your name]

Hi [Company name],

[item], reference [reference number], was promised back on [date promised], and that date has now passed without an update. I need a firm date this week, in writing, or I'll need to look at other options for getting this resolved.

[Your name]