I feel the same, although just with a practice test. I am also British, although I do have a relatively strong accent.
My scores were as follows:
Listening: 60
Reading: 63
Speaking: 27
Writing: 84
Grammar: 67
Oral Fluency: 10
Pronunciation: 10
Spelling: 19
Vocabulary: 49
Written Discourse: 90
This is putting me off taking a second practice or booking an actual test. I have contacted them to inquire about it and hopefully get a free practice test again, not holding my breath however.