Taxi drivers are total tossers. Friend of mine was hit by a taxi and the same thing happened there with the driver calling another taxi who then turned up and claimed to have seen the accident. Fortunately the taxis passengers backed my friend up and the police were pretty good about it.

Unfortunately from your description it does sound like you would be technically at fault. Speed is not a factor in collision blame. Would love you to go ahead and win but I fear you're off to start a losing battle.