The Dynamic Line Management (DLM) on FTTC is running 24/7 and makes decisions to slow down or speed up based on number of errors seen over time, so looks like the errors during the fault have been seen to be cleared by the DLM and speed given back.
Zen LLU should mean no changes in terms of what you order, but that with Zen network at the exchange they can pick up your data straight onto their network, reducing their costs and hence able to offer FTTC at prices close to the big providers.
FTTPoD comes on one flavour only - 330 down and 30 up and with a 3 year contract from Openreach. Install fee depends on distance from the aggregation node and minimum install is £750 if cab is outside, or a few thousand if further away, then an Openreach cost of £99/month (compared to £10 for the FTTC service), so often retails to the SME market at £150 to £200 per month.
It is a lot of money to gain the speed and stability, but it still cheaper than the old method of a dedicated leased line.