Ammonia Still At .25 Ppm

@Paddy60 You will probably find that Sue will give you detailed solution but a quick suggestion would be to check the pH. It may have crashed and be in the 6-6.5 region and this will stall the beneficial bacteria growth. If it has a water change to correct or baking soda to buffer the water will get you going again. Check back with the result and somebody will advise.
The chances are that once this is corrected the cycle will complete quire quickly.
You could also ask for some filter starter media, see the sticky Sue has posted

From Paddy60's duplicate thread (which he has now removed  )

.....just done a 75%water change to reduce nitrate in case this level  is slowing the cycle.

Is the ammonia reading still at 0.25 after the 75% water change? If it is, since there is zero nitrite I would suggest the cycle is finished. Ammonia can be difficult to distinguish between zero and 0.25.
To be certain, you could use this ammonia calculator. It will tell you how much of your total ammonia reading (ie the tester result) is in the toxic form. In the calculator, set salinity to zero and enter the rest of the data from your tank's results. Click calculate and look at the lower of the two boxes, NH3 concentration. If that is 0.02 or less, the cycle has finished.

Since pH is one of the things you need to enter in the calculator, you'll also find out if you've had a pH crash as Andy suggests. This does happen, I speak from experience 



Edit -
You posted the pH as I was typing. I've entered ammonia 0.25 and pH 8.0 in the calculator together with a temp of 25 deg C. The result is 0.0113 which is below the 0.02 safety limit. Even if the temp is as high as 30 deg C for cycling, the result is still below 0.02.
I'd say the cycle has finished. I know you've just done a big water change but another one about 25 to 30% should get rid of a lot of nitrate, then you can go fish shopping. Try to get nitrate down to tap water level.

For the calculation Sue entered your ammonia as 0.25, which is an over-estimation to be on the safe side, and the result is still less than 0.02. Sue says another water change then you are good to go.