Reply from the compliance department of my broker:
[salutation] "The orders in question were placed through a [redacted] managed route which had confirmed issues on Friday afternoon. [redacted] is our clearing firm, and orders placed on the web trading platform are managed by the [redacted] route. According to the web platform developers, during the last minutes of trading on Friday, they experienced an issue that resulted in some orders being delayed in processing. Some orders entered prior to 4:00 could not be processed until after the market closed, causing them to go into a 'Queued' state, and not be sent to the market. Those orders were released to the market on Monday morning. The developers of this 3rd party platform have confirmed that they are looking into the cause of this issue and will resolve it as quickly as possible. I sincerely apologize for the inconvenience caused." [signed]
That explains Friday.
On Monday, well that's another story. 1000 shares ordered. 40 minutes and 2 phone calls later order is finally executed. Excuse given: you clicked AON (all or nothing). I didn't think 1000 shares would take 40 minutes to put together.
It would appear there is no regulation stipulating the time in which a trade must be executed but there are reporting requirements. This is the link for the requirements:
Market Data 
Markets 
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