Spark: Iterating Through Dataframe with Operation - scala

Question

I have a dataframe and I want to iterate through every row of the dataframe. There are some columns in the dataframe that have leading characters of three quotations that indicate that they are accidentally chopped off, and need to all be part of one column. Therefore, I need to loop through all the rows in the dataframe, and if the column has the leading characters then it needs to join it's proper column.
The following works for a single line and gives the correct result:
val t = df.first.toSeq.toArray.toBuffer
while(t(5).toString.startsWith("\"\"\"")){
t(4) = t(4).toString.concat(t(5).toString)
t.remove(5)
}
However, when I try to go through the whole dataframe it errors out:
df.foreach(z =>
val t = z.toSeq.toArray.toBuffer
while(t(5).toString.startsWith("\"\"\"")){
t(4) = t(4).toString.concat(t(5).toString)
t.remove(5)
}
)
This errors out with this error message: <console>:2: error: illegal start of simple expression.
How do I correct this to make it work correctly? Why is this not correct?
Thanks!
Edit - Example Data (there are other columns in front):
+---+--------+----------+----------+---------+
|id | col4 | col5 | col6 | col7 |
+---+--------+----------+----------+---------+
| 1 | {blah} | service | null | null |
| 2 | { blah | """ blah | """blah} | service |
| 3 | { blah | """blah} | service | null |
+---+--------+----------+----------+---------+