What DazzaL proposed should work but if you can't change the input file in your case you can use this code :
declare
v_line varchar2(2000);
v_c1 varchar2(10);
v_c2 varchar2(10);
v_c3 varchar2(1980);
nb_line_per_record integer := 3;
v_line_in_record integer;
v_seperator varchar2(1) := ',';
v_file UTL_FILE.FILE_TYPE;
begin
v_file := utl_file.FOPEN(your_directory, 'your_file','r');
v_line_in_record := 0;
--we skip the first line
UTL_FILE.GET_LINE(v_file, v_line);
loop
v_line_in_record := v_line_in_record + 1;
begin
UTL_FILE.GET_LINE(v_file, v_line);
EXCEPTION
WHEN no_data_found THEN
exit;
END;
--first line of record we cut by v_seperator
if v_line_in_record = 1 then
v_c1 := substr(v_line,1,instr(v_line,v_seperator,1,1)-1);
v_c2 := substr(v_line,instr(v_line,v_seperator,1,1)+1,
instr(v_line,v_seperator,1,2)-
instr(v_line,v_seperator,1,1)-1);
v_c3 := substr(v_line,instr(v_line,v_seperator,1,2)+1)
|| char(10);--if you want new line in adresse
else
--not first line we concatanate to adress with new line
v_c3 := v_c3 || v_line ||
case when v_line_in_record = 2 then char(10) else '' end;
end if;
if v_line_in_record = 3 then
v_line_in_record := 0;
--do something with your record
insert into yourtable values (v_c1,v_c2,v_c3);
end if;
end loop;
UTL_FILE.FCLOSE(v_file);
COMMIT;
end;
But this would work only if you are absolutely certain that every record is 3 lines. If i were you i would add a record delimiter after each record and use SQLLOADER to load this file into a table. You can define a Record delimiter with SQLLOADER.Here is an exemple ctl which uses & as record delimiter
options (skip=1)
load data
infile "yourfile" "str '&'"
truncate into table your_table
fields terminated by ","
trailing nullcols
(heading1, heading2, heading3)
And if you use a Record delimiter you can even create an External Table on your file.