clutch fault???

hi all,
before i have my pants firmly pulled down i would like some input on a clutch fault with my 02 plate micra 1.4 p
the clutch was slipping and recently 3 weeks ago i had the cluch replaced by a garage who also said that the cable required replacing.
i started having problems with the bite on the pedal so fitted a new cable as reccommended by the garage
a day passed and the pedal felt spongy and hard to press so i rechecked the adjustment which was ok.
the cluch cable then pulled through the crimped sleeving leaving the pedal stuck down, so i took it back to the garage for them to look at it.
several days pass and i was told by the garage that i over adjusted the cluch cable thus burning the new clutch plate out.
holding my hands up i told them to replace the burnt out clutch and cable this time and paid again for the privelage. however the cluch bite was still spongy on collection and the pedal was sticking on the floor just like when i replaced the cable. several days pass and they confirmed that the clutch they fitted was incorrect so were going to reinburse me.
they change the clutch to the correct one and still encountered the same pedal issue. days pass and lots of scratching of heads
i now have the car back that has had a 2nd hand gearbox pedal box and 2nd hand cable ( who knows if the clutch is new or not ) fitted to it only to find out that they are saying it was the gearbox that has caused the problem all along and want me to pay for a 2nd hand gearbox and 3 hours labour!!!!
has anyone ever had this problem with the clutch pedal sticking to the floor and if so any input would be greatful
many thanks